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82 History of Art in Antiquity. The flat roof obtains to this day all over Persia. It is about one metre thick, and consists of pisi mixed with chopped straw beaten solid with the rammer. The roof of every house is provided with a stone roller* whose function is to repair the damages caused by the rains. This mode of covering has one drawback : continuous bad weather is apt to turn it into mud, and allow the water to percolate. On the other hand, as the material of which it conasts is a bad heat conductor, it serves better than any other mode of covering to keep the interior of the house comparatively cool. In the better class of houses the inconvenience attending on flat roofs is remedied to a certain extent. In the first place, they are tiled over, and have a slight incline at each side, whilst shallow grooves are provided to drain and carry off the water. We are convinced that some such precaution was resorted to in antiquity to save the gorgeous interiors of the royal palaces from utter devastation. The result could be obtained either by having the roof paved with bricks deltly put together and plastered over, or with huge tiles rimmed round, akin to those that were discovered at Susa among the dihris of the hypostyle hall of Artaxerxes, of which fine specimens are now in the Louvre. The general character of both roof and attic never varied, no matter the size of the buildini; over which they were placed ; when, however, the latter assiimeil colossal proportions, and the attic was carried round the four faces of the quincunx colonnade, the problem the artist had to solve became more difficult. Never- theless it was not above the capacity of the architect, whose fine f('elin^ for proportion is very apparent here. Tiiis it was that enabled him to understand that the dimensions of the columns must correspond with the amplitude of the entablature. In order to obtain his object, therefore, he went to the wood-yard for the finest beams he could find ; then he doubled or trebled the archi- trave, and put a frieze over it of the required heip^ht (we know the frieze from the fa(^ades of the tombs), and. still lurther to heighten the loft, he capped it with <i crenelation — a form which we shall prove from abundant d ita to have been traditional in Persian architecture, so that we are enabled to restore it with every appearance of probability. Then, too, the beams and planks had to be of sufficient calibre to carry the bed or beds of earth which would cover and protect the vast apartments beneath. Our Digitized by Google